Such engine-driven work machines are widely known as engine-driven generators used as a power source for construction work, a power source for outdoor recreation, a power source for emergency use, etc.
Furthermore, the arrangement of such an engine-driven work machine is already known as disclosed in Patent Publications 1 and 2, in which from the viewpoint of consideration to the surrounding environment when it is run, particularly when running at night in an urban area, in order to suppress running noise as much as possible the engine/work machine unit and the exhaust muffler are housed in a box, this box is provided with an air inlet and an air outlet opening on an outer face of the box and with a cooling air passage that reaches the air outlet from the air inlet while passing sequentially via the area around the engine/work machine unit and the area around the exhaust muffler, and a cooling fan is provided for generating a flow of air from the air inlet side to the air outlet side in the cooling air passage. Patent Publication 1: Japanese Utility Model Registration Publication No. 2-32836 Patent Publication 2: Japanese Patent No. 2539769